Units & Measurement Flashcards
Unit
An internationally accepted reference standard
Fundamental units
The units that can neither be derived nor further divided into simpler units
Derived units
Units obtained from fundamental units
SI System of Units
Systeme Internationale d’ Unites, is a standard scheme of internationally accepted symbols, units and abbreviations
What are the 7 base units?
Length, mass, time, electric current, thermo-dynamic temperature, amount of substance and luminous intensity
Measurement
Measurement of physical quantity is the comparing of this quantity with a standard amount of physical quantity of the same kind
Accuracy
How close a measured value is to actual value
Percision
How close measured values are to each other
Error
Uncertainty in measurement of physical quantity
Systematic errors
Errors that tend to be in single direction, otherwise uniform effect to the result. Types: Instrumental, Imperfection in technique, personal errors…
How to prevent systematic errors
Select better equipment, improving measuring techniques, following precautions, removing personal biases.
Mass of universe
10^55 kg
Random errors
Errors that occur somewhat irregularly
Least count error
Least value of an instrument is called least count. Least count error is associated with the resolution of the instrument. Errors that belong to the same category, but with a limited size.
Absolute Error
Δa1 = amean - a1
